In some crane lifting applications it is desirable to be able to connect to and release from the load without manual manipulation of the hook or latching mechanism. This ability is, for example, most critical in gantry cranes operated to raise and lower or lift clear and replace dam gates. In such situations the gate may be below water level or otherwise inaccessible to crane operating personnel. Prior mechanisms for automatically connecting to or disengaging a crane hook or latch without manual intervention are typically of a complicated nature requiring a high level of maintenance and frequently do not operate in an easy, reliable manner. Moreover, a gantry crane for handling dam gates may have its lifting beam submerged in water so that electrical or hydraulic control systems on the lifting cannot be used.
A further problem in cranes having a lifting beam which is positioned between the load object to be raised or lowered and an overhead hoist attached to the beam, such as is typically utilized in gantry cranes, is that the location of the connection of the load object to the beam through the connecting mechanism and the location of attachment of the hoist to the beam are spaced apart along the length of the beam. This space between these two locations results in bending forces on the beam which require it to have increased strength resulting in higher cost and undesired greater weight.